Method and apparatus for image forming capable of effectively fixing a toner image on a recording sheet by using induction heating

An image forming apparatus, comprising:

• means for forming a toner image on a recording sheet;
• and
• means for fixing the toner image on the recording sheet, the means for fixing comprising,
• means for creating a magnetic, and
• means for generating heat from the magnetic flux created by the means for creating, the means for generating heat having inner and outer circumferential surfaces and the means for creating faces the inner and outer circumferential surfaces.

An image forming method, comprising:

• forming a toner image on a recording sheet;
• and
• fixing the toner image on the recording sheet, the fixing comprising,
• creating a magnetic flux by applying an alternating current to a coil
• facing inner and outer surfaces of a heat generators,
• receiving the magnetic flux at the heat generator and generating heat there from to heat an associated fixing element to a predetermined temperature, and
• fixing the toner image on the recording sheet using the fixing element.

A fixing unit configured to fix a toner image on a recording sheet, comprising:

• a coil configured to receive a current to generate a magnetic flux, and
• a heat generator having inner and outer circumferential surfaces,
• wherein the coil faces the inner and outer circumferential surfaces, and
• wherein the heat generator is configured to generate heat by the magnetic flux generated by the coil.

An image forming apparatus, comprising:

• an image forming unit configured to form a toner image on a recording sheet;
• and
• a fixing unit configured to fix the toner image on the recording sheet, the fixing unit comprising:
• a magnetic flux generator including an exciting coil configured to generate a magnetic flux;
• and
• a heater configured to generate heat by the magnetic flux,
• wherein the exciting coil is disposed to surround an inner surface of the heater and an outer surface of the heater.

An image forming apparatus, comprising:

• an image forming unit configured to form a toner image on a recording sheet;
• and
• a fixing unit configured to fix the toner image on the recording sheet, the fixing unit comprising:
• a magnetic flux generator including an exciting coil configured to generate a magnetic flux and
• a heater configured to generate heat by the magnetic flux
• wherein the exciting coil is disposed to surround an inner surface of the heater and an outer surface of the heater, and wherein the heater has a Curie point not greater than 300 degrees centigrade.

An image forming apparatus, comprising:

• an image forming unit configured to form a toner image on a recording sheet;
• and
• a fixing unit configured to fix the toner image on the recording sheet, the fixing unit comprising:
• an induction heater configured to generate a magnetic field;
• and
• a heater configured to generate heat when placed in the magnetic filed,
• the induction heater comprising:
• an exciting coil;
• and
• a high frequency power source configured to apply a current to the exciting coil, wherein
• the heater has a Curie point not greater than 300 degrees centigrade, and wherein the heater starts rotating when a predetermined time period elapses after the high frequency power source is turned on, and
• the exciting coil is disposed to surround an inner surface of the heater and an outer surface of the heater.